In the
geologic timescale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...
, the Valanginian is an
age or
stage
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* Sta ...
of the
Early or Lower Cretaceous. It spans between 139.8 ± 3.0
Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the
Berriasian Stage of the Lower Cretaceous and precedes the
Hauterivian Stage of the Lower Cretaceous.
Stratigraphic definitions
The Valanginian was first described and named by
Édouard Desor in 1853. It is named after
Valangin
Valangin () is a former municipality in the district of Val-de-Ruz in the canton of Neuchâtel in Switzerland. On 1 January 2021 the former municipalities of Corcelles-Cormondrèche, Peseux and Valangin merged into the municipality of Neuchâte ...
, a small town north of
Neuchâtel in the
Jura Mountains of
Switzerland.
The base of the Valanginian is at the first appearance of
calpionellid species ''
Calpionellites darderi
''Calpionellites darderi'' is an extinct planktonic eukaryote and an important index fossil for the Lower Cretaceous stratigraphy. The first appearance of ''C. darderi'' marks the beginning of the Valanginian. It also defines the base of the "Cal ...
'' in the stratigraphic column. A global reference section (a
GSSP
A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...
) had in 2009 not yet been appointed.
The top of the Valanginian (the base of the Hauterivian) is at the first appearance of the
ammonite genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''
Acanthodiscus''.
Subdivision
The Valanginian is often subdivided in Lower and Upper substages. The Upper substage begins at the first appearance of ammonite species ''
Saynoceras verrucosum'' and the major
marine transgression Va3.
In the
Tethys domain, the Valanginian stage contains five ammonite
biozone
In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...
s:
* zone of ''
Criosarasinella furcillata''
* zone of ''
Neocomites peregrinus''
* zone of ''
Saynoceras verrucosum''
* zone of ''
Busnardoites campylotoxus''
* zone of ''
Tirnovella pertransiens''
Flora
The oldest fossils that can definitely be attributed to the clade
Angiospermae (flowering plants) are dated to the Late Valanginian.
References
Notes
Literature
*; (2004): A Geologic Time Scale 2004,
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer.
Cambridge University Pre ...
.
External links
GeoWhen Database - ValanginianMid-Cretaceous timescale
and ühttp://stratigraphy.science.purdue.edu/charts/Timeslices/5_JurCret.pdf Jurassic-Cretaceous timescale], at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Lower Cretaceous
at the website of Norges Network of offshore records of geology and stratigraphy
*02
Geological ages
Cretaceous geochronology
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